How to apply SMTP Authentication to my mail?

[simon2x1]

The code below is my mail code that send passsword to mail
but it does not go to yahoo and gmail i want to add STMP
authentication to it how can i do that.

<?php
		if(isset($_POST['submit'])){
	If(empty($_POST['email'])) {
	echo 'Please fill in the required fields!';
	
		}else{
			
			$email_to = $_POST['email'];
			$sql = "SELECT statue FROM statue WHERE mail='$email_to'";
			$result = mysql_query($sql);
			
				$count=mysql_num_rows($result);
				if($count==1){
				$rows = mysql_fetch_array($result);
				$your_password = $rows['statue'];

			$to = $email_to;
			$subject = "Your password here";
			$headers  = 'MIME-Version: 1.0' . "\r\n";
			$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
			$headers .="from: Alinke <support@mydomain.com>";
			

				$messages ="Here is your password : $your_password";
				$sentmail = mail($to,$subject,$messages,$headers);
				}else{
				echo 'your email can not be found in our database';
			}
			
				if($sentmail){
					echo 'Your password has been sent to your email address.';
				}else{
					echo 'Cannot send password to your e-mail address';
				}
		}
	}

?>

[simon2x1]

what if i do it like this will it work

  <?php
         if(isset($_POST['submit'])){
     If(empty($_POST['email'])) {
     echo 'Please fill in the required fields!';
  
         }else{
  
             $email_to = $_POST['email'];
             $sql = "SELECT statue FROM statue WHERE mail='$email_to'";
             $result = mysql_query($sql);
  
                 $count=mysql_num_rows($result);
                 if($count==1){
                 $rows = mysql_fetch_array($result);
                 $your_password = $rows['statue'];
  	

             $subject = "Your password here";
             $headers  = 'MIME-Version: 1.0' . "\r\n";
             $headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
             $headers .="from: Alinke <support@mydomain.com>";
  	
host = "mail.mymail.com";
 $username = "smtp_username";
 $password = "smtp_password";
 
 $headers = array ('From' => $from,
   'To' => $to,
   'Subject' => $subject);
 $smtp = Mail::factory('smtp',
   array ('host' => $host,
     'auth' => true,
     'username' => $username,
     'password' => $password));
 
 $mail = $smtp->send($to, $headers, $body);
             $to = $email_to;
  
                 $messages ="Here is your password : $your_password";
                 $sentmail = mail($to,$subject,$messages,$headers);
                 }else{
                 echo 'your email can not be found in our database';
             }
  
                 if($sentmail){
                     echo 'Your password has been sent to your email address.';
                 }else{
                     echo 'Cannot send password to your e-mail address';
                 }
         }
    }
  
 ?>